Inverse Design Of Silicon Based Photonic Devices Based On Coded Metamaterials

In recent years,silicon-based photonic devices has been developing rapidly.However,because of the diffraction limit,the development of silicon-based photonic devices have been hindered in the aspect of size.Surface plasmon polaritons(SPPs)can break through the diffraction limit,the scale of photonic devices based SPPs can reach nanometer level,which provides the possibility for making finer micro-nano photonic devices.As a bridge connecting the silicon waveguide and the SPPs waveguide,coupler for silicon and plasmonic waveguides(CSPW),has received extensive attention.However,in recent years,there is a certain need to improve the coupling efficiency and bandwidth of CSPW.What’s more,in previous work,the integrated optical devices usually can only realize one of the functions of coupling or power splitting,but rarely can realize the function of efficient mode conversion and flexible power splitting at the same time.Inverse design technology has been proved to effectively improve the performance of photonic devices by optimizing the structure of the device,but there is little research on reverse design of silicon waveguide-SPPs waveguide couplers.In this thesis,photonic devices based on silicon-based coding metamaterials(SCM)structure are proposed.The specific research contents and innovations are as follows:1.We have designed a CSPW based on SCM,which can couple silicon waveguide and SPPs waveguide relatively efficiently.In this thesis,genetic algorithm,binary particle swarm optimization,simulated annealing and multi-traversal direct binary search algorithm(MDBS)are used to inverse optimize the SCM in CSPW,and has achieved certain improvement in coupling efficiency and bandwidth.The simulation results prove that in the bandwidth range of 1.45 μm to 1.65 μm,the coupling efficiency of the optimized CSPW is above 93%,and the bandwidth and coupling efficiency are currently competitive.In addition,CSPW also reverse designed by optimization algorithms under different parameter settings,and discusses the.influence of algorithm parameters on the optimization results.2.Based on the CSPW with SCM,we propose an SPPs power splitter(PPS)that can realize the function of coupling and achieve any ratio of power splitting simultaneously.The split SPPs can be directionally coupled and transmitted along two directions,which has strong flexibility.MDBS algorithm is used to design PPS inversely,the simulation results prove when the ideal splitting ratio is 50%:50%,65%:35%,40%:60%,the actual average splitting power is 44.18%:41.65%,57.11%:28.69%,32.73%:49.37%from 1.50 μm to 1.60 μm,respectively.In summary,we have designed two kinds of SPPs photonic devices based on SCM,and optimize devices inversely,which achieve the improvement in performance.The proposed photonic devices in theises have relatively high flexibility,and can be widely used in surface plasmon-based optical chips.